322 ALASKAN GLACIER STUDIES
seemed to shake the mountains on either side of us. We must have been at least 15 miles from Barry Glacier, and yet we could distinctly hear the icebergs falling from it into the sea." In May, 1898, Castner went up Barry Arm "to within a hah* mile of the sea end of the great glacier. Photographs were taken and the interesting manufacture of icebergs watched. The latter consisted of a breaking off and tumbling into the sea of tons of blue ice from the face of the glacier, accompanied by the roar of a Niagara, as the berg started on its ocean voyage, eventually to melt and become a part of the tides which now carried it away."
This description by Castner, with the mention of the great size of icebergs and the noises heard by Glenn from as far as Yale Glacier, a phenomenon not observed in 1910, are quoted because they suggest some very great activity in 1898. Field evidence, observed in 1910, in connection with a study of the distribution of the vegetation, independently fixed 1898 as the date of the last great activity, which seems to have ceased before the visit of the Harriman Expedition the following year.
It is possible that Barry Glacier barred Harriman Fiord in 1898, perhaps all but touching Pt. Doran. But the absence of a barren zone on Pt. Doran proves that the glacier did not actually rest upon this point. This is probably because of the extremely strong tides which were observed here even in 1910 after Barry Glacier had retreated Sj miles. In 1899 the glacier front stood about f of a mile from Pt. Doran, as Gan-nett's map shows. The narrative and photographs by members of the Harriman Expedition indicate that the discharge of large icebergs, and the unusual noises observed by Castner and Glenn a year before, had ceased. Gilbert's description of the 1899 conditions is as follows:
"Barry Glacier, at the entrance to the fiord, approaches from the north-northeast. Its low grade indicates a distant source . . . it impressed the beholder as one of the largest ice rivers of Port Wells. Its peculiar relation to the fiord causes it to be swept by the passing tide and prevents the accumulation of icebergs about its front, but the same relation exposes it to exceptionally rapid melting by the sea, and the conflict of ice current with tidal current must be active. The forward flow of the ice tends to narrow the strait, and this constriction, by increasing the speed of the tide, enhances the melting power of the water. The fact that the glacier was able to occupy two thirds of the width of the fiord indicates that its forward movement was strong.
"Its moraines were of small relative importance, but a belt along the western margin was darkened by drift and there were two medials. One of the latter, exhibited in section in the face of the cliff, was seen to be the surface outcrop of a sheet of drift-charged ice which extended obliquely downward, passing under the western portion of the stream.
"The cliff was further diversified by a number of caves at the water's edge, supposed to be the mouths of englacial streams.
"Connected with the eastern edge of the ice was a long, narrow tongue attached to the shore (PI. CXXX, A), evidently a remnant left by the glacier at some very recent date when its front was more extensive. As this strip was not protected by gravel, it must have been wasting rapidly, and the period of its separation may have been only a few months. I was in doubt whether to ascribe it to a progressive shrinkage of the glacier or to seasonal variation. On the same coast the forest did not approach the glacier closely at the water line, but passed above it, leaving a barren zone